Increasing Reaction Temperature Research Articles

Influence of coal slime on migration behavior and ecological risk of heavy metals during hydrothermal carbonation of sewage sludge

The heavy metals (HMs) presented in sewage sludge (SS) limit the application of SS hydrochar. Compare to SS, coal slime (CS) contains higher carbon, silicates and aluminates. Addition of CS during the hydrothermal carbonization (HTC) of SS can improve the quality of hydrochar, and facilitates better solidification of HMs. In this paper, the influence of CS on migration behavior and ecological risk of HMs during HTC of SS was investigated, and the environmental risks associated with HMs in co-hydrochar was assessed. The results showed that adding CS during SS HTC could lower the content of HMs in co-hydrochar, and compared to the total content of Cd, Cr, Cu and Zn in SS-240-1, the total contents of these HMs in S5C5-240-1 decreased by approximately 43.8, 51.6, 36.5, 42.8%, respectively. The addition of CS also could facilitate the transformation of HMs from bioavailable fractions to relatively stable fractions. The leaching concentration and bioavailability of HMs in hydrochar decreased substantially with the increase of reaction temperature and residence time, and the leaching concentration of Ni in S5C5-280-1 decreased by 83.7%, and the bioavailability concentration decreased by 89.5%. Interestingly, the results also showed that co-HTC of CS and SS could effectively reduce the ecological risk and the potential contamination level associated with HMs in hydrochar, and then reduced the potential environmental risk. The results of this study may provide theoretical basis for the solidification of HMs in hydrochar, as well as for clean and efficient utilization of SS and CS.

Hydrogen production and elemental migration during supercritical water gasification of food waste digestate

The rapid growth of food waste (FW) is a huge challenge on a global scale, and anaerobic digestion is one of the most commonly used methods to deal with food waste, and the increasing amount of food waste digestate (FWD) produced by anaerobic digestion also poses a huge challenge to waste management. This paper explores supercritical water gasification (SCWG) as a valuable and innovative strategy for the conversion of FWD into H2-rich syngas. The research focuses on analyzing the effects of reaction temperature and residence time on syngas production, gas composition, element migration (C, N and P) during the SCWG process. Experimental results show that as the reaction temperature increases from 400 °C to 500 °C, the total syngas yield increases significantly, from 2.4 mol/kg to 9.7 mol/kg, especially the yields of H2, CO2, and CH4. As the reaction temperature increases and the residence time increases, the migration of carbon from the solid and liquid phases to the gas phase accelerates with increasing temperature and residence time, resulting in a higher proportion of carbon in the gas phase. In terms of liquid phase composition, nitrogenous compounds are significantly converted into ammonium (NH4+-N) at higher temperatures. In addition, the organic phosphorus is observed transferring into inorganic phosphorus, which are mainly apatite. This study explores the scalability of SCWG and its potential for the production of clean fuels, thereby contributing to the sustainable management of FWD.

Unveiling the role of temperature on structural, compositional, morphological, thermal and optical properties of hydrothermally synthesized SnS2 nanostructures

Recently, the layered metal dichalcogenides (LMDs) such as tin disulfide (SnS2) has engrossed significant attention because of their n-type semiconducting tunable properties. A hydrothermal method was employed for the synthesis of SnS2 nanostructures by varying reaction temperatures i.e. 160, 170 and 180 °C. To determine the crystallographic, micro-structural, morphological, elemental compositions, thermal and optical properties of the prepared samples, various characterizations such as XRD, Raman spectroscopy, FTIR, FESEM, EDS XPS, TGA, PL and UV spectroscopy were employed. The structural analysis revealed the hexagonal phase formation of prepared SnS2 nanostructures with space group symmetry of P63mc (layer group no.: 186) in all the prepared samples. The sample prepared at 160 °C also exhibit orthorhombic crystal phase of SnS along with SnS2 crystal phase. The intensity of diffraction peaks increased with rise in growth temperature which infers the crystallinity improvement and crystallite size growth. Raman and FTIR spectroscopy also confirm the formation of SnS2 phase in synthesized samples. FESEM analysis showed the development of hexagonal shaped nanostructures for all the prepared samples. Elemental analysis showed the improvement of stoichiometry of SnS2 with increase in reaction temperature. XPS results inferred the existence of Sn and S with +4 and −2 energy states respectively, confirmed the formation of SnS2. The optical property analysis shows the emission in visible region. Furthermore, the band gap values get decreased i.e. 2.42 eV–2.34 eV with increase in growth temperature. Also, the refractive index of the synthesized samples was determined by various empirical models. The improvement of linear optical susceptibility (χ(1)), nonlinear refractive index (n2) and nonlinear optical susceptibility (χ(3)) suggest the usefulness of synthesized nanostructures in optical and photonic applications. Engineering of different properties of SnS2 nanostructures with reaction temperatures suggests the potential usage of these nanostructures for optoelectronic applications.

Support induced effects on the activity and stability of Ga2O3 based catalysts for the CO2-assisted oxidative dehydrogenation of propane

The influence of the support nature (Al2O3, TiO2, SiO2) on the activity and stability of supported Ga2O3 (10 wt%) catalysts was investigated for the production of propylene through the CO2-assisted oxidative dehydrogenation of propane (CO2-ODP). Catalytic activity was found to be higher when gallium oxide was dispersed on alumina support which was characterized by the highest acid site density and moderate surface basicity. Below 650 °C propylene yield increased in the order Ga2O3-TiO2<Ga2O3-SiO2<Ga2O3-Al2O3, which was modified as Ga2O3-Al2O3<Ga2O3-TiO2<Ga2O3-SiO2 for higher reaction temperatures. Propylene selectivity decreased with increasing reaction temperature followed by an increase of ethylene and methane selectivity implying that the side reactions of propane hydrogenolysis and propane/propylene decomposition were facilitated at higher temperatures hindering the CO2-ODP reaction. Gallium oxide catalysts supported on TiO2 and SiO2 exhibited sufficient stability for 30-35 hours on stream at 660 and 710 οC, contrary to Ga2O3-Al2O3 which although was stable at 710 οC it was gradually deactivated when the reaction was taking place at 600 °C. Temperature programmed oxidation experiments showed that carbon deposition was favored over Ga2O3-Al2O3 catalyst when the reaction was conducted at low temperature, which may be related to the higher surface acidity of this sample and be responsible for its deactivation with time. SEM images and elemental mapping obtained from both the freshly prepared and used Ga2O3-MxOy samples showed that Ga and M (M: Si, Ti, Al) were uniformly present even after prolonged catalyst interaction with the reaction mixture. EDS analysis indicated that carbon formation was accelerated with increasing reaction temperature.

Study on Reaction Behavior and Phase Transformation Regularity of Montmorillonite in High-Calcium Sodium Aluminate Solution System

The diaspore is a typical representative of bauxite resources in China, which is the primary raw material for the Bayer process in alumina production, particularly in regions such as Shanxi, Guangxi, Guizhou, and Henan. Clarifying the phase transformations and reaction mechanisms of the silicon-containing minerals during the Bayer leaching process of diaspore is essential for improving the efficiency of alumina production. This article focuses on montmorillonite, which is one of the silicon-containing minerals of diaspore-type bauxite, investigating the reaction mechanisms and phase changes of montmorillonite under the high-calcium sodium aluminate solution system by using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Magic Angle Spinning Nuclear Magnetic Resonance (MAS–NMR) and Fourier Transform Infrared Spectroscopy (FTIR). The results show that montmorillonite dissolved and transformed into Na6(AlSiO4)6 (hydrated sodium aluminosilicate) under the high-calcium sodium aluminate solution system, and calcium oxide and sodium aluminate in the solution reacted to form (CaO)3Al2O3(H2O)6 (hydrated calcium aluminate). With the increase of reaction temperature, caustic alkali concentration (Nk), and reaction time, hydrated calcium aluminate and hydrated sodium aluminosilicate react and transform into Ca3Al2SiO4(OH)8 (hydrogarnet). Under the optimal reaction conditions of a 120 min reaction time, a temperature of 240 °C, an Nk of 240 g/L, and a CaO–to–SiO2 mass ratio (C/S) of 3.5:1, the montmorillonite reaction degree can reach a maximum of 93.71%.

Efficient Extraction and Analysis of Wheat Straw Lignin by Response Surface Methodology

To enhance the high-value utilization of straw waste and achieve efficient lignin extraction, wheat straw was selected as the feedstock for investigating the effects of reaction temperature, reaction time, solid–liquid ratio, and formic acid concentration on lignin yield using a formic acid/acetic acid solvent system. A single-factor experimental design was initially employed, followed by optimization using the response surface methodology. Additionally, a kinetic model was developed to describe lignin extraction kinetics in the formic acid/acetic acid system. The structural characteristics and thermal stability of the extracted lignin were analyzed via FTIR, UV spectroscopy, and TGA. The findings indicate that increasing reaction temperature, reaction time, solid–liquid ratio, and formic acid content all significantly enhanced lignin extraction yield from wheat straw, with the primary influencing factors being reaction temperature &gt; solid–liquid ratio &gt; reaction time &gt; formic acid content. The optimal extraction conditions were identified at a reaction temperature of 90 °C, a reaction time of 3.5 h, a solid–liquid ratio of 1:16.5, and a formic acid content of 86.2 wt.%, yielding a lignin content of 79.83%. The analytical results demonstrated that the extracted lignin preserved the structural integrity of the original lignin and exhibited good thermal stability.

Controlled chemical transformation of lignin by nitric acid treatment and carbonization

This study focuses on understanding the chemical reactions and results of Kraft lignin transformation through nitric acid treatment and subsequent carbonization. With its rich carbon content, lignin stands out as a promising candidate for the manufacturing of high-value carbon materials. The lignin underwent effective nitration, depolymerization, and oxidation under ambient conditions and at 40 °C, while a slight increase in reaction temperature significantly reduced the reaction time. The molecular weight Mw was effectively reduced from 4371 g/mol to 767 g/mol. The acid-treated lignin samples with incorporated nitro groups were further carbonized to create nitrogen-doped carbon structures. The resulting materials show stable nitrogen content (about at 5 wt%) even after carbonization due to the transformation of nitro groups into thermally stable pyridinic moieties, thereby exhibiting enhanced electrocatalytic properties compared to nitrogen-free carbon materials derived from Kraft lignin. The nitric acid-assisted treatment of lignin obviates the need for catalysts, and additional extraction or purification steps for preparing bio-derived carbon precursors, rendering it facile, fast, and cost-efficient.

Synthesis and characterization of Selenicereus undatus extract mediated nano-Bi2O3 and its application in the adsorption of Rhodamine B dye

Betacyanins (BC) are reddish-purple pigments widely found in the peels of white-fleshed dragon fruit (Selenicereus undatus) and peels and pulps of red-fleshed dragon fruit (Selenicereus costaricensis). BC pigments are good anti-oxidants that inhibit the formation of reactive oxygen species (ROS) in plants and thereby promote the reduction of metal ions to zero-valent metals. It also acts as a good stabilizing and capping agent in the synthesis of nanoparticles. Hence, this research aims to extract, and quantize the content of BC from the peels of Selenicereus undatus, to fabricate betacyanin-rich- Selenicereus undatus (SU) modified bismuth oxide nanoparticles (Bi2O3 NPs) and characterize using UV-Vis, FTIR, XRD, SEM, EDAX, and BET. The quantity and stability of the betacyanin are optimized using various parameters like time, temperature, solvent ratio, pH, etc., through a UV-Vis spectrophotometer at 538 nm. Synthesized SU-Bi2O3 NPs aim to alleviate synthetic dye contaminants through adsorption- an efficient route for water remediation. The nano-adsorbent Bi2O3 NPs showed an increase in dye adsorption with an increase in reaction time, temperature, and Bi2O3 NPs dosage, enabling efficient removal of dyes such as Rhodamine B (RhB) dyes.

A novel bio-based epoxy resin curing agent of gluconic aldehyde amine for the preparation of epoxy resin film

To resolve the shortage of fossil resources, gluconic aldehyde amine (GAA) was prepared from glucose via Mannich reaction, and then was used to cure E901 epoxy resin to prepare glucose-based epoxy resin film (GAAF). Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy indicated the successful synthesis of GAA. With the increase of Mannich reaction temperature, the tensile strength and elongation at break of GAAF firstly increased and then decreased, as well as the thermal stability increased. The GAAF-60 sample exhibited maximum tensile strength of 47.5 MPa, which were higher than that prepared by petroleum-based phenolic amine and lignin-based phenolic amine, respectively. The synthesis of GAA presented a novel bio-based epoxy resin curing agent for the preparation of epoxy resin film.

Sonochemical synthesis of mesoporous ZnyCd1-yS quantum dots: Composition-dependent optical, electrical, dielectric, and hydrogen-generation characteristics

Mesoporous ZnyCd1-yS quantum dots (QDs) with mixed cubic–hexagonal phases prepared by sonochemical technique at varying Zn content. Incorporating Zn ions in the CdS lattice reduced the crystalline size and enhanced the corresponding surface areas at increasing Zn contents. The increase of Zn content in ZnyCd1-yS QDs increased the bandgap from 2.52 eV to 3.83 eV and enhanced the corresponding Urbach energy from 72 meV to 279 meV. ZnyCd1-yS QDs exhibited small electrical activation energies ranging from 249 mV to 361 mV. The effect of Zn content on the catalytic activity of ZnyCd1-yS QDs toward hydrogen production through NaBH4 hydrolysis was investigated at different temperatures. Ternary alloys ZnCdS QDs exhibited higher catalytic activity than pure ZnS and CdS QDs, with Zn0·5Cd0·5S QDs displaying the highest hydrogen generation rate of 96 mL∙min−1 g−1. The increase of reaction temperature from 30 °C to 60 °C enhanced the rate constant of hydrogen production from 0.071 to 0.36 min−1. Based on the pseudo-first-order equation, the estimated apparent activation energy of Zn0·5Cd0·5S QDs was 45.3 kJ mol−1. Overall, the obtained results underscored the potential of ZnyCd1-yS QDs as promising catalysts for hydrogen generation.

Evaluating Alkali Activation in Magnesium Slag Carbonization and Its Mechanism

In recent years, magnesium slag has been used as a raw material for solid waste treatment using the carbonization method and has proven to be promising in reducing carbon emissions. In this study, the alkali activation reaction was introduced to promote the carbonization of magnesium slag. The resulting mechanical properties, microstructural attributes, and carbonization mechanism were studied by varying the sodium hydroxide content, temperature, and carbon dioxide concentration during the reaction process. The results showed that the amounts of calcium hydroxide, C-S-H, and calcium carbonate in the reaction products increased with the sodium hydroxide content, which enhanced the compressive strength of the composite. However, it does not influence the carbonization mechanism with the increasing reaction temperature, which only elevates the reaction rate. With the increase in the carbon dioxide concentration during alkali activation, the carbonization reaction is dominated by the amount of CO2 dissolved in the reaction medium, and the carbonization mechanism is changed. Thus, a significant decrease in the calcium hydroxide content and a sharp increase in the calcium carbonate content in the products occurred, which significantly improved the compressive strength of the resulting magnesium slag composite. Among them, the maximum compressive strength is 6.83 MPa.

Sonodynamic inactivation of gram-negative and gram-positive bacteria in the presence of phenothiazine compounds toluidine blue and azurin A

BackgroundSonodynamic antimicrobial chemotherapy (SACT) is an effective antimicrobial treatment that can avoid the production of drug-resistant bacteria. Design and development of new high-efficiency sonosensitizers play a key role in the practical application of SACT. MethodsThe bacteriostatic effects of two phenothiazine compounds, toluidine blue (TB) and azure A (AA) combined with ultrasonic (US) on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were studied, and the sonodynamic antibacterial activities of TB and AA were compared. The reactive oxygen species (ROS) and the types of ROS produced in the sonodynamic system were detected and the sonodynamic mechanisms of TB and AA were proposed. ResultsThe sonodynamic bacteriostasis mediated by TB and AA increased with the increasing concentration of sonosensitizer, the extension of sonication time and the increase of reaction temperature. The production of ROS was the main reason that TB and AA had excellent sonodynamic antibacterial performance. Singlet oxygen (1O2) and hydroxyl radical (•OH) were the main ROS types in the sonodynamic antibacterial system. The ROS produced by the combined action of AA and US was higher than that of TB. ConclusionBoth TB and AA displayed excellent sonodynamic antibacterial activities. Moreover, AA had a higher sonodynamic activity than TB. The electron donation effect and steric hindrance effect of the methyl group of phenothiazine parent nucleus of TB might be the cause of the decrease of its sonodynamic activity. These results would provide a valuable reference for the further study of phenothiazines sonosensitizers and their clinical application in SACT.

Optimization of ethylene and propylene yields from n-hexane catalytic cracking over H-ZSM-5 catalyst using model based design of experiments (DOE)

Catalytic cracking of n-paraffins of varied carbon chain length (C6-C11) to represent light naphtha and gasoline was studied using extrudates of H-ZSM-5 (zeolite: binder = 70: 30) as a catalyst in a fixed bed reactor. Optimization of ethylene and propylene yields using model-based design of experiments (DOE) was carried out for n-hexane cracking by varying the temperature (550–650℃), weight hourly space velocity (3.3–9.9 h−1) and carrier gas (N2) flowrates (3–10 L/h). These variables showed significant effect on the conversion of n-hexane and yield of ethylene and propylene under studied reaction conditions. The Box-Behnken design coupled with response surface methodology was used to determine the effect of reaction temperature, WHSV and N2 flow rate on the yield of ethylene and propylene. Empirical models were constructed for the response variables namely n-hexane conversion, ethylene (E) yield, propylene (P) yield and total ethylene and propylene (E+P) yield. Main effect plot showed that the average yield of ethylene and propylene increased with increase in reaction temperature and decreased with increase in WHSV. The optimization study of multiple responses showed maximum 94.7% conversion of n-hexane and 46.1 wt% yield of ethylene and propylene at 650℃ catalyst bed temperature, 3.3 h−1 WHSV and 8.3 L/h N2 flow rate. The model predicted ethylene and propylene yields matched closely with experimental data for catalytic cracking of naphtha feed at 550 and 650℃ cracking temperature.

Bio-oil production from hydrothermal liquefaction of algal biomass: Effects of feedstock properties and reaction parameters

In this study, two different algal biomass types, including fresh algal biomass (HS) and dewatered algal biomass (TH and CH), were selected to explore the effects of their properties and hydrothermal liquefaction (HTL) reaction parameters on bio-oil yields and quality. The obtained results showed higher bio-oil yields through the HTL process of the HS algal biomass than those obtained from the TH and CH algal biomass. The observed bio-oil yields increasing-decreasing trends with increasing reaction temperatures and times. The optimal reaction temperature and time were 325 °C and 30 min, respectively. These conditions resulted in HS, TH, and CH algal biomass bio-oil yields of 31.6, 24.2, and 14.4 wt%, respectively. The HS algal biomass-derived bio-oil exhibited higher H/C ratios and HHV values, as well as lower N/C ratios, than those of the dewatered algal biomass-derived bio-oils. The bio-oil composition results demonstrated the enhancement effects of flocculant additions to the dewatered algal biomass on the bio-oil fractions. The TH and CH algal biomass-derived bio-oils exhibited substantially higher hydrocarbon contents than those in bio-oils of the HS algal biomass. In addition, the nitrogenous compound and hydrocarbon contents exhibited decreasing and increasing trends, respectively, with increasing reaction temperatures from 275 to 325 °C, improving the bio-oil quality.

Study on the cracking process of epoxy resin under oxygen and water atmosphere based on ReaxFF force field

Amino-cured epoxy resins are widely used in the electrical and electronic industry for their excellent properties. To investigate the mechanism of the effect of O2 and H2O on the pyrolysis behavior of epoxy resin, in this paper, the cross-linked structure of bisphenol A type epoxy resin cured by adducts of diethylenetriamine and butyl glycidyl ether is modeled based on the ReaxFF force field, and the thermal decomposition processes at different temperatures and gas atmospheres were simulated and the pathways of the small molecule products were clarified. The results show that epoxy resin will produce small molecule gas products, such as H2, CO, H2O, OH, CH2O, and free radicals, in the process of pyrolysis; the presence of amino groups also generates nitrogen-containing radicals, such as CN, CH2N, and C2H4N; as the reaction temperature increases, the rate of pyrolysis reaction will be accelerated. The same temperature in oxygen and water atmospheres can accelerate the breakage of epoxy resin main chain by promoting the breakage of carbon and oxygen bonds and, at the same time, promote the generation of small molecule gases, such as H2 and CO.

Thermodynamic and economic comparisons of supercritical water oxidation and gasification of oily sludge under hydrothermal flames

Dual-shell reactors using hydrothermal flames as internal heat source were proposed for supercritical water gasification (SCWG) and oxidation (SCWO) of oily sludge to achieve fast preheating and avoid corrosion, salt plugging, and overheating. The SCWG and SCWO systems with hydrogen-rich syngas and electricity outputs, respectively, were established and simulated using Aspen Plus 11. Simulation models were validated by comparing with experimental products and temperature profiles. The maximum exergy destruction coefficients of 28.01% and 24.31% appear in the combustion reactor for both the SCWG and SCWO systems, respectively, indicating the indirect preheating method with hydrothermal flame is critical to the energy efficiency. The increase of reaction temperature promotes hydrogen but inhibits methane formation in the SCWG, and more steam but less syngas is output at higher reaction temperatures. Although more steam and electricity outputs are present at higher reaction temperatures for the SCWO, more fuel input is required. Lower exergy efficiencies are obtained at higher reaction temperatures in both the SCWG and SCWO systems for more energy is output as low grade steam. Less fuel input is required for both the SCWG and SCWO systems at higher feed concentrations, and higher exergy efficiencies can be obtained. The net treatment cost for the SCWG and SCWO systems are 119.19 and 215.47 USD/t, respectively, indicating the SCWG is more economically competitive compared with the SCWO.

Dissolution behavior and kinetic investigation of in solution in the reaction of colemanite ore with propionic acid

Colemanite ore, which is one of the most significant commercially substantial boron minerals, is used to produce various boron compounds in the industry with its rich B_2 O_3 content. Calcium propionate, used in the food industry, is formed as a by-product in its production. In the production of boric acid from colemanite, the use of different solvent reagents is at the forefront to prevent the formation of Mg^(2+), Ca^(2+) and SO_4^(2-) impurities and borogypsum by-products. For this reason, in our study, the dissolution kinetics of colemanite ore in propionic acid solution in an aqueous medium were carried out in a batch reactor system. As dissolution parameters; reaction temperature, solid/liquid ratio, propionic acid (CH_3 CH_2 COOH) concentration, stirring speed and particle size were selected as. According to the experimental results, the amount of Mg^(2+) passed to the solution; was observed that the solution increased with the increase in reaction temperature with the decrease in solid-liquid ratio, grain size, and acid concentration. In addition, it was determined that the mixing speed was not effective. Obtained experimental data were analyzed according to homogeneous and heterogeneous reaction models using the Statistica 10.0 package program. It was determined that the dissolution kinetic of Mg^(2+) passing to solution conformed to the "Avrami model" and activation energy (E) was calculated as 8.18 kJ⁄mol.

Unraveling the Complexities of Silica Nanoparticle Adsorption onto Polymer Latexes in Pickering Emulsion Polymerization.

Incorporating unmodified silica nanoparticles onto polymer latexes to fabricate aqueous polymer dispersions without relying on electrostatic attraction during the Pickering emulsion polymerization process still faces challenges. For negatively charged silica nanoparticles to successfully adsorb onto polymer latexes, particularly in an anionic initiator emulsion polymerization system, they have remained elusive without the use of auxiliary monomers and cationic initiators. This study investigates various experimental parameters, such as emulsion polymerization temperature, monomer solubility, salt concentration, and cation type, to elucidate the factors influencing the adsorption of unmodified silica nanoparticles in Pickering emulsion polymerization. While poly(methyl methacrylate) (PMMA)/SiO2 hybrid latexes can be obtained under pH conditions of 5-6 and at temperatures of 65 °C or below, the loading rate of silica nanoparticles decreases as the reaction temperature increases, resulting in bare PMMA latexes without silica nanoparticle adsorption at temperatures exceeding 70 °C. Introducing styrene (St) into the monomer mixture with methyl methacrylate in a ratio of up to 10 wt % leads to a gradual decrease in silica nanoparticle loading rate, from 27.3 to 8.2 wt %, attributed to the low solubility of St in water. Furthermore, the presence of sodium ions (Na+) is found to be crucial for silica nanoparticle adsorption onto PMMA latexes, as the sodium ions have a stabilizing effect on both the silica nanoparticles and the silica nanoparticle-armored latexes. These findings highlight the complex nature of Pickering emulsion polymerization in the presence of unmodified silica nanoparticles, demonstrating that the loading rate of silica nanoparticles onto polymer latexes is influenced by various factors. These insights pave the way for developing aqueous polymer dispersions with high silica nanoparticle loading rates onto polymer latexes, which is a desirable trait in the coating industry.

Study on strength and reduction characteristics of iron ore powder-green carbon composite briquettes

The metallurgical industry is a key sector for carbon emissions, and in recent years, there has been widespread attention on the use of biomass resources as a green, renewable, and carbon–neutral energy source material for low carbon ironmaking processes. The waste wood after hydrothermal-pyrolysis carbonization has the characteristics of low content of harmful elements and high content of fixed carbon. In this study, the waste wood after hydrothermal-pyrolysis two-step carbonization treatment was used as a reducing agent for the reduction of iron ore to prepare iron ore powder- green carbon composite briquettes (ICCB) with two carbon–oxygen ratios. The study investigated the effects of reduction behavior and reaction temperature on the reduction performance of the ICCB. The results indicate that with the increase in reaction temperature, the volume of the ICCB gradually contracts, leading to a reduction in mass. The shrinkage rate of the ICCB during self-reduction at 1200℃ is significantly higher than during co-reduction, and the shrinkage effect of the C/O 0.5 ICCB is more pronounced than that of the C/O 0.8 ICCB. Due to the excessive carbon content in the C/O 0.8 ICCB, the carbon cannot be fully consumed during the reaction process, resulting in consistently low compressive strength of the ICCB, with a compressive strength of 12 N after reduction at 1200℃. In contrast, the iron phase in the C/O 0.5 ICCB gradually recrystallizes during the reduction process, ultimately yielding plastic iron briquettes with compressive strengths exceeding 3000 N after different reaction behaviors at 1200℃. In summary, reducing the carbon-to-oxygen ratio and increasing the reaction temperature contribute to the volume contraction and enhanced compressive strength of the ICCB during the reduction process.

Parameter optimization of ultrafine molybdenum powder during hydrogen reduction of MoO2 based on central composite design method

The hydrogen reduction of MoO2 is a common method for preparing ultrafine molybdenum powder, which is an important basic material for manufacturing high-performance Mo-based alloys. However, its preparation parameters are usually hard to be controlled. To address this issue, the work conducted the parameter optimization research during the hydrogen reduction process with using central composite design method, and the influence of different parameters such as reaction temperature, yttrium content, and hydrogen flow rate, on the particle size and oxygen content of the prepared molybdenum powder were investigated. The findings showed that the particle size of the prepared molybdenum powder is gradually decreased with the increase of reaction temperature and yttrium content, while gradually increased with the increase of hydrogen flow rate. The oxygen content of the prepared molybdenum powder is gradually decreased with the increase of reaction temperature and hydrogen flow rate, while gradually increased with the increase of yttrium content. Reaction temperature and yttrium content have significant interactions on the particle size and oxygen content are also concluded, and their respective regression model equations are obtained. The result also demonstrated that the particle size and oxygen content of the prepared molybdenum powder had a certain contradictory relationship. Through the comprehensive analysis, the optimal parameters for preparing ultrafine molybdenum powder with a low oxygen content are deduced, that is, reaction temperature: 1200 K, yttrium content: 0.1 mass%, and hydrogen flow rate: 1000 mL/min. Under the conditions, the average particle size and oxygen content of the prepared molybdenum powder are 320 nm and 0.456 mass%, respectively.